Sentences with phrase «isotopic composition»

On the basis of anomalous isotopic compositions of oxygen and magnesium, 14 oxide grains from two primitive meteorites (Bishunpur and Semarkona) have been identified as circumstellar condensates.

It is possible to reconstruct past precipitation changes by measuring the stable hydrogen isotopic composition in terrestrial plant waxes because rainfall is the primary source of hydrogen stored in plant material.

LeGrande, A.N., 2006: The Climate Imprint on the Oxygen Isotopic Composition of Water: Observations, Proxies, and Coupled Isotopic Model Simulations.

To carry out the study, the researchers developed a new sample extraction and mass spectrometry method that allowed them to precisely measure the carbon isotopic composition of methane in very small ice core samples.

However, researchers don't really know the true hydrogen isotopic composition of Earth's water, says Lydia Hallis, a planetary scientist at the University of Glasgow in the United Kingdom and lead author of the new study.

CO2 produced from burning fossil fuels or burning forests has quite a different isotopic composition from CO2 in the atmosphere.

A warm - blooded animal will therefore have a different isotopic composition from a cold - blooded animal that shares the same environment.

The stable isotopic composition of the carbon in carbon dioxide over the last 24,000 years illuminates past carbon cycle behavior.

Instead of CO2 concentrations being about 15 p.p.m.v. lower, the CO2 / temperature shift can also be explained by isotopic composition overestimating temperature by about 1 °C.

«Tropospheric N2O isotopic composition: Instrumentation development and preliminary data for the constraint of the N2O global budget and stratospheric influence» by Kat Potter Pros: A clever and simple idea.

Differences in isotopic composition between certain therapsids and other contemporary species showed that eight species from two different lineages of therapsids were already endo - homeothermic several million years before the Permian - Triassic extinction event.

The dental morphology, wear, and enamel isotopic composition of the Aramis kudu species are all consistent with such placement.

And Hallis suspects that the deepest, most primitive material in the mantle should have an even lighter isotopic composition than the inclusions her team measured.

«All natural samples have a similar isotopic composition of uranium, but the uranium in Curious Marie has six percent more 235U, a finding that can only be explained by live 247Cm in the early solar system.»

A collision between two large planetary objects with unique isotopic compositions is thought to have created the Earth - Moon system.

Isotopic composition also helped rule out the solar wind as the source, since the solar wind has far less Carbon - 13 than what was found in the sample.

«During photosynthesis plants bind atmospheric carbon, whose isotopic composition is preserved in resins over millions of years, and from this, we can infer atmospheric oxygen concentrations,» explains Ralf Tappert.

«Sediment cores in Arctic lakes show that there have been significant 20th - century declines in the nitrogen isotopic composition of organic nitrogen,» Steig said.

The project continued time - series observations of atmospheric carbon dioxide and isotopic composition begun by Charles D. Keeling at remote sites, including Mauna Loa, the South Pole, and eight other sites.

The net rate of CH4 emissions is generally estimated from three approaches: (1) extrapolation from direct flux measurements and observations, (2) process - based modelling (bottom - up approach) and (3) inverse modelling that relies on spatially distributed, temporally continuous observations of concentration, and in some cases isotopic composition in the atmosphere (top - down approach).

LeGrande, A.N., and G.A. Schmidt, 2006: Global gridded data set of the oxygen isotopic composition in seawater.

The hydrogen and carbon isotopic composition of methane from natural gases of various origins

The measurements show that 4 - Vesta contains the same hydrogen isotopic composition as carbonaceous chondrites, which is also that of Earth.

Therefore, animals that feed on tropical open - environment grasses (or on grass - eating animals) have different isotopic compositions from those feeding on browse, seeds, or fruit from shrubs or trees.

This isn't to say that the tree rings have the same isotopic composition as the atmosphere — as noted above, plants have a preference for the lighter isotopes, but as long as that preference doesn't change much, the tree - ring changes wiil track the atmospheric changes.

However, both the driving force and the climate reconstructions over the pre-industrial era are based on the analysis of the natural archives of climate sensitive quantities, such as the growth of trees and seashells, and the changes of chemical, biological, and isotopic compositions in lake sediments and ice core samples.

Stable isotopic compositions — variants of particular chemical elements — of such remains, recovered from soil and lake sediment, may help us better understand climate change over a long span of time.

Oakwood, the tragedy is not what's happening in science — things there are just as they should be: the field continues to develop new data and refined analyses, general conclusions have been reached that a very large majority support, based on well - established principles (properties of CO2, thermodynamics, effects of warmer air on evaporation...) and data (measures of CO2 levels, shifts in isotopic composition of atmospheric CO2, temperature records — instrumental and proxy,...).

The researchers brought together 90 fossils discovered in South Africa, Lesotho, Morocco and China, 63 of which were therapsids belonging to 22 different species, in order to study their oxygen isotopic composition.

For example, it can be used to discern climate data from the isotopic composition of fossil foraminifera in (well - preserved) ocean drill cores.

The researchers measured the chemical and isotopic compositions of water samples collected monthly from 23 locations along West Virginia's Upper Mud River and its tributaries between May and December 2012.

«Measuring the isotopic composition and concentrations of argon and neon trapped in new minerals that have formed at mantle depths can help us to understand where these noble gases originated,» Baldwin says.

Dust found in the ice gives a record of what was in the air thousands of years ago, whether from volcanic eruptions or human activity, and the isotopic composition of the hydrogen and oxygen molecules in the snow give a record of the temperature of the earth at the time.

The isotopic composition studies had created an «isotopic crisis» for the hypothesis.

In 2001, however, a team of scientists reported that the isotopic compositions of a variety of elements in terrestrial and lunar rocks are nearly identical.

But planetary bodies that formed in different parts of the solar system generally have different isotopic compositions, so different that the isotopic signatures serve as «fingerprints» for planets and meteorites from the same body.

But more accurate measurements of oxygen isotopes published in 2016 only confirmed that the isotopic compositions are not distinguishable.

Paleontologists will focus especially on the chemical and isotopic composition of Lyuba's baby tusks.

To do that, Saal and his colleagues looked at the isotopic composition of the hydrogen trapped in the inclusions.

They plan to explore what other traces of elements are present in the inclusions, as well as make measurements of the isotopic composition of some elements, which could reveal exactly how the metal forms and how it interacts with rocks in the mantle.

This is a particularly useful region because the oxygen isotopic composition of the seawater is largely determined by the flow of water through the Strait of Gibraltar, which in turn is sensitive to changes in global sea level — in a way like the pinching of a hosepipe.

By contrast, in transpiration, plants simply suck water out of the soil and push it into the air without changing its isotopic composition.

Unlike previous methods, the clumped isotope paleothermometer technique does not rely on assumptions about the isotopic composition of seawater.